Process of filling leather and the resulting product



Patented Oct. 22, 1935 UNITED STATES raoc'nss or FILLING LEATHER mm m ansonrmc raonuc'r Lester M. Whitmore, Salem, Va, asslgnor to Lea and Mcvitty, Inc., Philadelphia, Pa.I a corporation of Delaware No Drawing. Application July 2'3, W84, Serial No. 737,290

14 Claims.

My invention relates to an improved leather product and to the process of making it, and more particularly it relates to an improved leather product, especially applicable as a heavy sole 3 leather.

One object of my invention is to provide a leather product of increased solidity, and increased thickness and weight, which properties are obtained in the leather without the necessity of loading the product with a water-soluble filler as has previously been the case.

A further object of my invention is to furnish to the trade a leather, particularly adapted for use as sole leather, which possesses high wearresistant qualities and high resistance to water penetration and to the softening efiects normally encountered in the presence of moisture or high humidities.

Still another object of my invention is to provide a leather with a marked decrease in the tendency of the product to air-burn during the drying operation and for the tanning extracts to bleed to surface during drying or when the I product is worked in a damp condition.

These and other objects including the provision of a novel process of preparing the leather product will be apparent hereinafter from a consideration of the specification and claims.

Heretofore in the tanning of leather with the natural vegetable tanning extracts, particularly those containing catechol tanning materials, diificulties have been encountered in the process, and in the manufacture of heavy leathers, particularly sole leather, various water soluble materials as fillers have been added to the leather during the process in an attempt to increase the solidity, thickness, weight, and resistance to wear and water penetration. Due to the solubility of the vegetable tanning agents in water-and of the water soluble fillers, these materials during manufacture tend to bleed to the surface, particularly during drying or when the leather is worked in a damp condition. Additionally,the leather tends to air-bum during the drying resulting in an inferior product. Furthermore, the finished product, due to the presence of watersoluble material therein, is not characterized by high resistance to wear or water penetration since in the presence of moisture or high humidities,

50 a dissolving action on the watersoluble material takes place.

The process of the present invention overcomes or reduces to a minimum all of the disadvantages of the previous processes, and the product possesses properties which have previously been sought but have only been obtained to a small degree.

In the process of the present invention, the active tanning agents of the extracts are converted chemically into insoluble products which a are then retained permanently between and on the fibres and fibrils of the leather. The chemical conversion of the tanning agents into insoluble material is brought about by a reaction between them, an aldehyde and an ammonium l0 salt. Since the active tanning agent after periormlng its tanning function is rendered insoluble, there is no tendency for the leather to bleed or to air-burn. Furthermore, the finished product, due to the presence of the insoluble material therein, possesses increased weight, thickness, solidity. and resistance to wear. The product also oflers a higher resistance to water penetration and to softening in the presence of moisture or high humidities. The reaction of the tanning 10 agents with the aldehyde and the ammonium salt also gives an antiseptic efiect to the leather which reduces the growth of molds normally encountered with damp leather. By the process of the present invention, a leather is easily obtained having a degree of tannage of to or even higher based on the relation between combined tannin and hide substance as determined by the oflicial method of the American Leather Chemists Association, which as higher than that previously such products.

The process of the present invention may be carried out with any type of hide and any of the usual vegetable tanning extracts, particularly 3 those containing catechol tannins, may be used as the tanning material. For example, the following materials or extracts have been found to be applicable for use:-mangrove, wattle, quebracho 3% blsulphlted, quebracho 6% bisulphited; gambier, hemlock, cutch, chestnut, chestnut oak, myrabolans, valonia, divi-divi, and the like. The aldehyde which is employed preferabLv is formaldehyde due to its availability and cheapness but other aldehydes including acetaldehyde, turfuraldehyde, and benzaldehyde may be used. Any salt containing the ammonium radical will satisfactorily react, for example, ammonium sulphate, ammonium chloride, ammonium oxalate, or ammonium phosphate. to

The, reaction of the aldehyde and the ammonium salt with the tanning agents to deposit insoluble material between and on the fibers and fibrils of the leather is not strictly speaking a tanning process but rather a filling or finishing encountered in will be recognized 80 sirable that the treatment with the aldehyde.

process since the hide is tanned as previously with the tanning agent. The amount of tanning agent employed and the steps of the tanning process may be the same as has previously beenthe practice with the particular type of hide to be tanned and the particular type of leather to be manufactured. The order of addition of the materials is immaterial but it is deshall take place after the leather has been tanned, at least to some extent, and the process is particularly applicable for the treatment of tanned leather. The three reactants may be add ed simultaneously but preferably the aldehyde is not added until the tanning extracts have been absorbed by the hide or leather. The ammonium salt may be added with the tanning agent, simultaneously with the aldehyde, or thereafter. The aldehyde and/or ammonium salt may be reacted with the tanning extract in the wheel, drum, temper bath, dry dip, or elsewhere in the process.

The amounts of tanning extract, aldehyde, and ammonium salt employed are not critical and depend upon the degree of improvement desired.

In general, it has been found advisable to use at least 3% to 4% of aldehyde, and about 5% of the ammonium salt on the basis of dry extract to obtain the optimum results, but additional amounts of these materials are not detrimental to the leather. As examples, the following proportions have been found to give satisfactory results:

50 cubic centimeters of 40 Twaddell clarified quebracho extract, 1 gram of ammonium chloride, and 4 cubic centimeters of commercial 40% formaldehyde solution; or 50 cubic centimeters of 40 Twaddell clarified quebracho extract, .5 grams of ammonium chloride, and 5 cubic centimeters of commercial 40% formaldehyde solution.

The following specific examples are given merely by way of illustration, and it will be obvious that many variations may be made therein without departing from the essential features of the invention.

Example I Leather is drummed in the usual manner with quebracho extract to which has been added 5% of ammonium sulphate on the dry basis.- The stock is piled down over night to absorb the load and bleached to clear the surface of the leather. It is then dipped fifteen minutes in a solution of formaldehyde containing 20% of this ingredient,

piled over night to react and fix, and then oiled off and finished in the usual manner.

Example II Rough dry leather which has had one wheel load is dry dipped in a '15 Barkometer dry dip consisting of 95 parts of clarified quebracho and 5 parts of anmionium sulphate on a dry basis. Coming from the dry dip, the leather is dipped fifteen minutes in a solution of 20% formaldehyde and is then given an oil wheel load of Ep-,

som salts, sugar, and 011, set out, and finished in accordance with the usual practice.

Example III Leather from the yard may be drummed with dipped if desired in the usual manner to give additional water soluble load, after which it is finished as usual. 1 1

In some instances, it will be found desirable to react the formaldehyde remaining in contact with 5 the leather after the completion of the reaction "with a compound capable of converting it into pound or an amonia derivative such as urea may be mentioned.

I claim: 1. The process of filling leather which comprises reacting a vegetable tanning extract, aldehyde', and an ammonium salt together between and on the fibres and fibrils of leather to deposit an insoluble material therebetween and thereon.

2. The process of filling leather which comprises reacting a vegetable tanning extract containing a catechol tannin, formaldehyde, and

an ammonium salt together between and on the fibres and fibrils of leather to deposit an insoluble material therebetween and th'ereon.

3. The process of filling leather which comprises reacting a vegetable tanning extract con- 80 taining a catechol tannin, formaldehyde, and ammonium sulphate together between and on the fibres and fibrils of leather to deposit "an insoluble material therebetween and thereon.

4. The process of filling leather which com- 86 prises reacting a vegetable tanning extract, aldehyde, and an ammonium salt together between and on the fibres and fibrils of leather to deposit an insoluble material therebetween and thereon, the aldehyde being present in the 40 neighborhood of 3% to 4% and the ammonium salt being present in the neighborhood of 5% 4 figured as ammonium sulphate and based on the dryextract.

5. The process of filling leather which oomprises reacting a vegetable tanning extract containing a catechol tannin, formaldehyde, and an ammonium salt. together between and on the fibres and fibrils of leather to deposit an insoluble material therebetween and thereon, the 60 formaldehyde being present in the neighborhood of 3% to 4% and the ammonium salt being present in the neighborhood of 5% figured as ammonium sulphate and based on the dry extract.

6. The process of filling leather which comprises reacting a vegetable tanning extract containing a catechol tannin, formaldehyde, and ammonium sulphate together between and on the fibres and fibrils of leather to deposit an insoluble material therebetween and thereon, the aldehyde being present in the neighborhood of 3% to 4% and the ammonium sulphate being present in the neighborhood of 5% based on the dry extract.

7. The process of filling leather which comprises absorbing a vegetable tanning extract between and on the fibres and fibrils of leather, and thereafter reacting an aldehyde and an ammonium salt therewith to deposit an insoluble material between and on said fibres and fibrils. 10

8. The process of filling leather which comprises absorbing a vegetable tanning extract containing a catechol tannin between and on the fibres and fibrils of leather, and thereafter reacting formaldehyde and an ammonium salt thereamazes 3 with to deposit an insoluble material between and containing the insoluble reaction product of 1 and on said fibres and fibrils. a vegetable tannin extract, an aldehyde, and an 9. Filled leather containing the insoluble reammonium salt between and on the fibres and action product of a vegetable tannin extract, an fibrils thereof.

aldehyde, and an ammonium salt between and 13. Filled leather having a degree of tannage 5 on the fibres and fibrils thereof. of at least 110 determined by the ofllcial method 10. Filled leather containing the insoluble reof the American Leather Chemists Association,

action product of a vegetable tannin extract conand containing the insoluble reaction product of taining a catechol tannin, formaldehyde, and an a vegetable tannin extract containing a catechol ammonium salt between and on the fibres and tannin, formaldehyde, and an ammonium salt be- 10 fibrils thereof. tween and on the fibres and fibrils thereof.

11. Filled leather containing the insoluble re- 14. Filled leather having a degree of tannage of action product of a vegetable tannin extract conat least 110 determined by the ofiicial method taining a catechol tannin, formaldehyde,andamof the American Leather Chemists Association, monium sulphate between and on the fibres and and containing the insoluble reaction product of i5 fibrils thereof. a vegetable tannin extract containing a catechol 12. Filled leather having a degree of tarmage tannin, formaldehyde, and ammonium sulphate of at least 110 determined by the oflicial method between and on the fibres and fibrils thereof.

of the American Leather Chemists Association, LESTER M. WHITMORE. 

